Tag Archives: water in the garden

The battle with the water weeds

We have dropped the water level for me to hand scoop the stream

We have dropped the water level for me to hand scoop the stream

I have been getting really down and dirty this week, hand pulling the weed from our main stream. As this involves wading in mud up to my knees, I emerge looking decidedly worse for the wear and no, you are not going to see a photo of me in this state.

Our main issues are with dreaded oxygen weed, Cape Pond weed and blanket weed. If we didn’t stay on top of them, the entire water surface would disappear below vegetation, which rather defeats the purpose of having a stream in the garden. I asked Mark if he thought our problems were related to farm run-off and excessive nitrogen but he is of the opinion that it has more to do with slow water flow rates, though he felt the build up of mud and silt in our streambed would be extremely fertile. When we get sudden bright green algal bloom, it is an indication of nitrogen being applied on farms upstream.

The worst offenders: Cape pond weed and oxygen weed

The worst offenders: Cape pond weed and oxygen weed

There is something very appealing about a natural stream but they are not without their problems. Offhand, I thought of three gardening colleagues with natural streams. One has problems with flooding in torrential rain. The water cannot get away fast enough so it builds up on his property. One has no problem at all with flooding because their stream is in a deep ravine, maybe 20 metres below the level of their land, but this means it isn’t really a significant garden feature. The third has a picturesque mountain brook to die for, bar two factors. Their land has sufficient natural fall to clear flood waters quickly but the bubbling brook can turn into a torrent that scours everything alongside. This means that they can’t have streamside plantings of any quality. They tried two or three times before giving up, having seen the plants ripped out and carried away. Their second issue is that the water is of high purity so a number of neighbours have water rights granted. Each neighbour has installed their own alkathene pipe at the top of our friends’ garden where the stream enters, running the pipes along the streambed until they exit at their adjoining properties down the bottom. There must be at least five alkathene pipes, both black and garish white, visible in that stream. It is not a good look.

So be careful what you wish for. None of these people, however, have to do what we do and clear the waterway of vegetation every year or two. We eliminated problems with flooding and scouring but our water flow is not sufficient to stop the growth of water weed. Our wonderfully natural looking stream is actually the result of outside expertise and in-house experience coming up with a low tech solution. We control the water where it enters our property by means of a simple weir. In normal conditions, this allows the water to flow equally down two streambeds. One meanders pleasantly through our park while the other is a deeper flood channel girded by stop banks. The two stream beds join up again on the other side of our property so the flow downstream is completely unaffected. When heavy rains cause flooding, a mechanism is triggered which directs all the water down the flood channel. By these simple means, we eliminated flooding, boggy patches and scouring from the park though we do have to manually reset the weir in order to get the water flowing again.

The pond weed is the direct result of having a relatively low flow through the park area, though our stream is such that it never dries up. Oxygen weed is a curse. We had a bad infestation which Mark finally eliminated entirely for some years. He blames the reinfestation on people emptying unwanted goldfish bowls into the stream at the corner by the road. Do not ever do this. The goldfish are most likely to die but the oxygen weed is an invasive menace in slow moving water.

Our other great burden comes from a former neighbour who, as far as Mark is concerned, should be lined up and shot for liberating such an invasive weed. African Cape Pondweed, also known as water hawthorn, (botanically Aponogeton distachyum) is undeniably pretty, with a very long flowering season. Presumably this is why the former neighbour planted it on the margins of his ponds. Because he had no control over the water flow, the inevitable floods scoured it all out of his place but it found a lovely home in our slow moving sections. I don’t know how many hundreds of hours we have spent rooting it out. It is quite good friends with the oxygen weed because it can grow through it and spread its lily pad-like leaves. Between them they have the potential to turn our stream to bog. Native weeds are nowhere near as aggressive.

It is only yours truly who has shed most clothes to get in and hand pull the water weeds this year. Generally this is done by the two men in my gardening life (Mark and Lloyd) who take it in turns to wield the long handled rake and manually haul it all out on to the bank. It is a slow process and pretty hard on their backs. I thought it would be faster and easier to do it by getting in and so it is proving to be. The water is pleasantly warm, the mud even more so on sunny days. I just have to time my mud wrestling because I can’t exactly stop for lunch or a cuppa. Wisecracks about eels are not welcome.

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

Lloyd at least stays cleaner on the end of the rake but it is harder on the back

First published in the Waikato Times and reproduced here with their permission.

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The pitfalls and perils of garden water features

It may be a natural stream in our park but it is hardly an easy care water feature

It may be a natural stream in our park but it is hardly an easy care water feature

Water is an important inclusion in any garden, or so the common wisdom says. We laughed when Joe Swift on BBC Gardener’s World commented that he hated water features because they were rarely maintained. Water is difficult to manage well.

A natural stream might seem the best option for the lucky ones and on a fine day, the mountain brook that bounces its way through Ngamamaku Garden is indeed a source of envy for many of us. The trouble is that with our torrential downpours, natural streams can quickly become raging torrents which take out all your plantings. Tony has long since given up using treasures in his stream-side plantings. They disappear in the flood torrents. We have the upper reaches of the Waiau Stream running through our park and again, it is charming and a great asset. Because we control the flood waters by some simple but time honoured techniques (a weir and a flood channel), we don’t get the scouring but it takes constant management to prevent it all silting up and regular, heavy work to keep the water weeds under control – particularly oxygen weed and Cape Pond Weed.

Ponds – are ponds easier? Possibly the larger your pond, the more self maintaining it becomes though you generally need fish (commonly goldfish) to keep the mosquito larvae at bay. By definition here, a lake is sufficiently large to allow water skiing, or at least canoeing. If it is not of that dimension, it is a pond. Maybe a large pond, but a pond. By the time your pond has shrunk below about a metre square or round, it can’t really be called a pond any longer. A puddle, perhaps, or a basin? If you have a natural pond fed by a spring, it may stay fresher and relatively stable through the seasons. Home made ponds can be difficult. Firstly they are prone to developing leaks and that is a terminal condition unless you remedy the problem – which is never easy to do. Shallow ponds are problematic because the water heats up and that encourages algae growth. If it is too deep (somewhere about 40cm), you have to fence it. Basically a pond, by definition, is a static body of water which will therefore go stagnant. And homemade ponds are often lined in polythene which is really hard to manage so it is not visible in any way at any time – folds of polythene just look really tacky.

The formal pond that depends on pristine water quality shrieks out money. I have seen a couple and essentially they are the same as running a swimming pool – dependent on a full filtration system and frequent vacuuming. I have a few ethical issues with their sustainability and personally that swimming pool look does not strike me as aesthetically pleasing. It is all a bit too Beverley Hills. If you are going to have something that looks akin to a swimming pool, it may as well combine function with form and be a swimming pool. I also particularly dislike the hum of the pump as a background sound in the garden. To do it properly, you need a silent pump. The same goes for any water feature which relies on moving water to a part of your property where it does not naturally occur. Circulating the water does at least solve the problem of it becoming stagnant but it is a fraught activity, more often prone to lapses in taste and poor management. Fountains? A matter of taste. Repro classical fountains don’t do it for me. I have seen enough of the real thing in European gardens, which is where they belong – usually in the gardens of royalty or at least wealthy nobility. The increasing democratisation of the classic fountain hasn’t done much for its aesthetics. They are just a little “Look at me! Look at me!” in the average New Zealand garden. Leave them for Versailles.

The overseas fashion for rills or narrow canals has been slower to catch on here. I think the origins for these lie in Islamic gardens – the requirement to wash before frequent prayers. In recent years, English garden designers rediscovered them and you see the ribbon of lawn bisected with the water channel, often only 20cm wide. Hmmm. The words drainage channel and lacking in purpose spring to mind so we will say no more on the topic.

Mark has a mantra that design features in a garden need a logic to them, they need to make sense in the context. So creating a naturalistic waterfall cascading down from a dry hillside is a contradiction in itself. The fountain in the formal garden is not pretending to be natural – it is all about the imposition of human will and design on nature. The waterfall is trying to simulate a natural event so it needs to be as close to seamless as possible, not, as more often happens, a feature plonked in to “add interest” with little regard to logical context. Being able to hear the pump thrumming away as it circulates the water makes it even worse.

None of the above is to deny that it is possible to do water features well and when they are done well, they are a welcome addition to the garden, whether it be a reflecting pool, the sound of a babbling brook or cascading water, a formal design feature or a modest goldfish pond. The mistake is to think that they are mandatory and once in place, that they need no attention. And I own up to the fact that we have a formal goldfish pond which is severely afflicted by algal bloom at the moment.

The simplest type of water feature - in this case a stone millwheel with a bung in the base so it can be drained and refilled easily

The simplest type of water feature - in this case a stone millwheel with a bung in the base so it can be drained and refilled easily

A word on safety: we have all had it drummed in to us that children can drown in as little as 7.5cm of water, which means they can drown in a puddle, really. We were told by an inspector some years ago that the reason so many little ones drown in swimming pools is because they are attracted by the blue colour that is the norm and that once in, they instinctively try to reach the bottom to stand up. Vertical sides also make it near impossible to get out. These aspects do not generally apply to garden water features but if the safety aspects worry you, it may be better to dispense with the feature altogether rather than try and net it over.

If you absolutely must have water and your garden is small, a large container with some sort of plug or bung system to enable drainage is probably the most easy-care solution. You can then replace the water when the mosquito larvae start swimming around or it all turns green and yukky. If you plan anything more ambitious, think carefully before you start and be prepared to maintain it.

How ironical is it that one of the very best examples of gardening we have seen internationally is Beth Chatto’s dry garden in the UK? The dry, gravel garden at Hyde Hall nearby is also shaping up brilliantly. Mind you, both are in very arid, stony areas. Similar plants would rot out in our higher rainfall and humid conditions. But generally it is better to garden with the conditions and not to feel that one simply must introduce a water feature to counteract the dry areas.